City of Detroit

Stormwater Management Design Manual

CityMichiganhighNo

Other manuals in Michigan: Michigan

Document Metadata

Jurisdiction level

municipality

“The City of Detroit's Stormwater Management Design Manual (Design Manual) encompasses the engineering methods and technical standards that Detroit's development community and property owners need”
Chapter 1, Page 1-1

State

Michigan

“EGLE: Michigan Nonpoint Source Best Management Practices (BMP) Manual”
Chapter 1, Page 1-8

Version / edition

July 2025

“July 2025”
Title Page

Adoption / effective date

2025-07

“July 2025”
Title Page / Design Manual Edit History

Last revised date

2025-07

“July 2025 • Chapter 1: Pages 1-3, 1-5 • Chapter 2: Pages 2-6...”
Design Manual Edit History

Relationship to state manual

independent

“Although this Design Manual is the only technical resource crafted specifically for Detroit's PCSWMO compliance, there are other stormwater management resources with a statewide perspective... The information contained within the manual is informational only and should not be construed as requirements for Detroit's PCSWMO.”
Chapter 1, Section 1.4, Pages 1-8 to 1-9

Design Criteria

Design storm return periods (years)

1-year, 2-year, 5-year, 10-year, 25-year, 50-year, 100-year

“Table 4-1 Precipitation Depths* (inches) for Recurrence Interval (years) Duration 1 year 2 year 5 year 10 year 25 year 50 year 100 year”
Chapter 4, Table 4-1, Page 4-2

Water quality volume method

Treat or retain the 90th-percentile annual non-exceedance storm (1.0 inch) over the Regulated Area: (1) remove 80% TSS from uncontrolled post-construction runoff during a 1.0-inch rain event, or (2) effluent TSS ≤80 mg/L, or (3) Volume Control—retain (infiltrate or store/reuse) 1.0 inch of runoff over the Regulated Area (meeting retention automatically satisfies TSS). MS4 Channel Protection also requires the larger of 1.0-inch retention or volume needed to limit 2-year/24-hour runoff to pre-development. Flood control: post-construction peak ≤0.15 cfs/acre for the 10-year/24-hour (<5 ac Regulated Area) or 100-year/24-hour (≥5 ac).

“TSS Control (1) Remove 80% of the total suspended solids (TSS) projected to be in uncontrolled runoff from the Regulated Area in the post-construction condition during a 1.0-inch rain event, or; (2) Have an effluent TSS concentration of less than or equal to 80 mg/L ... or; (3) Satisfy the Volume Control requirement below; this automatically meets the TSS requirement. Volume Control Retain* the runoff volume generated by 1.0 inch over the Regulated Area”
Chapter 2, Table 2-1, Page 2-5

Peak flow calculation method(s)

Rational Method, Modified Rational Method, Simple Method (1-inch and 1.9-inch retention/extended detention volumes), NRCS Curve Number Approach, Small Storm Hydrology, NRCS Midwest-Southeast (MSE) Type 3 rainfall distribution, EPA SWMM / SWMM-based hydrograph routing

“Table 4-5 Computational Methods... Rational Method, EPA SWMM, HydroCAD, StormCAD... Simple Method for 1-inch storm... Modified Rational Method... NRCS Curve Number Approach, EPA SWMM, HEC-HMS, TR-55, TR-20”
Chapter 4, Table 4-5, Page 4-9

Required hydrologic/hydraulic software

EPA SWMM, HydroCAD, StormCAD, HEC-HMS, TR-55, TR-20

“Rational Method, EPA SWMM, HydroCAD, StormCAD, or other DWSD-approved model... NRCS Curve Number Approach, EPA SWMM, HEC-HMS, TR-55, TR-20, HydroCAD, StormCAD, or other DWSD-approved model”
Chapter 4, Table 4-5, Page 4-9

Approved BMP categories

Detention Practices (basic detention basins, extended dry detention, extended wet detention), Bioretention (including bioswales and tree box filters), Infiltration Practices (infiltration basins and trenches), Permeable Pavement (porous asphalt, pervious concrete, pervious pavers, grid pavement), Rainwater Harvesting / Cisterns, Living Roofs and Walls (green roofs and walls), Stormwater Wetlands, Manufactured Treatment Devices (hydrodynamic separators and filtering systems), Trees for Stormwater Management / Green Space

“Chapter 7 – Detention Practices... Chapter 8 – Bioretention... Chapter 9 – Infiltration Practices... Chapter 10 – Permeable Pavement... Chapter 11 – Water Harvesting... Chapter 12 – Green Roofs and Walls... Chapter 13 – Stormwater Wetlands... Chapter 14 – Manufactured Treatment Devices... Chapter 15 – Trees for Stormwater Management”
Chapter 1, Section 1.3 / Table of Contents, Pages 1-6 to 1-8